I think a starting stack like 12/12/5/11/3 for T30K is required. Going with 8/8/... for a HORSE game is not an option in my opinion.
Then you can check for the structure of the WSOP HORSE events back when starting stack was 30K.
For the tournament duration, I would then play with level duration.
I play HORSE tourneys every year. Just played a circuit event HORSE last night in fact. I think the circuit event schedule posted above is a decent place to start with. I would add in a few more levels though for playability, and start with deeper stacks. 20k to 30k would be ideal. Maybe shorter time limits for the early rounds though, otherwise you'll be playing all night. Rotate the game every 8 hands (not every x minutes).